This invention relates to a thermosetting resin composition, and more particularly relates to a thermosetting resin composition obtained by dissolving a polybutadiene which is a backbone chain containing pendant tricyclodecenyl-.alpha.,.beta.-unsaturated groups having polymerizable double bonds in a polymerizable monomer and having good workability.
Polybutadienes having hydroxyl groups and a number average molecular weight of about 1000 to 5000 are called liquid polybutadienes and have fluidity at normal temperatures, so that they are tried to be used in various applications such as, by using as a chain extender isocyanates, sealants, caulking materials, adhesives, potting materials, paints, and the like. This is also because liquid polybutadienes have good elastomeric properties, adhesiveness, and electrical properties. Although they have fluidity, their viscosity at 25.degree. C. are 50 to 600 poises and further toxicity of isocyanates becomes a recent problem to be solved. Therefore, liquid polybutadienes are not used for general purposes.
On the other hand, Japanese Patent Appln. Kokoku (Post-Exam Publn.) Nos. 26950/71 and 8261/73 propose processes for producing thermosetting resins having good workability by using polybutadienes having functional groups in place of the alcohol component or the acid component of unsaturated polyesters so as to improve brittleness of conventional unsaturated polyesters, said brittleness being a defect of unsaturated polyesters, without decreasing properties of polybutadienes. But according to the process of Japanese Patent Appln. Kokoku (Post-Exam Publn. ) No. 26950/71, gelation easily takes place during the esterification reaction due to the double bonds of polybutadiene, so that sufficient degree of condensation cannot be obtained and thus the properties of polybutadienes hardly be applied. According to the process of Japanese Patent Appln. Kokoku (Post-Exam Publn.) No. 8261/73, since a hydrogenated polybutadiene is used in order to improve the defect mentioned above, production cost becomes expensive. Therefore, the two processes mentioned above are not used for general purposes.
Japanese Patent Appln. Kokoku (Post-Exam Publn.) No. 16195/72 discloses a process for producing a thermosetting resin having excellent workability by using a polybutadiene having active hydrogen and an isocyanate and introducing acryl or methacryl groups into the resin. But since the acryl or methacryl group generally has poor copolymerizability with styrene and the like, rapid and sufficient curing at normal temperatures cannot be obtained unlike unsaturated polyester resins and physical properties of the resulting cured articles are also insufficient.
Thus general-purpose thermosetting polybutadienes without losing excellent properties of polybutadienes as elastomer, having excellent workability and being easily cured at normal temperatures, in other words, being easily handled, have long been desired.
The present inventors have extensively studied modification of polybutadienes and accomplished this invention by providing a thermosetting resin composition improved in the defects mentioned above.